David Walliams and Johnny Vegas provide voices in educational St John Ambulance ad

The TV ad, called "the chokeables", features animated small objects such as a pen lid, a crayon and a marble, explaining how to save a choking baby.

Vegas provides the voice for a red jelly baby, which explains that the objects are fed up of real babies choking on them. The jelly baby then turns blue as he has trouble breathing.

A small princess toy, with a voiceover from Walliams, shows the correct technique to save the jelly baby.

St John Ambulance said it decided to move away from hard-hitting ads as it found that almost 80 per cent of parents would not know how to save their baby’s life if it was to choke.

The work has been created by Bartle Bogle Hegarty London, with creative direction from Matt Doman and Ian Heartfield. It was directed by Si & Ad through Academy. The media planning and buying was handled by John Ayling & Associates.

St John Ambulance is offering its supporters and social media followers a preview of the campaign on 11 January before it launches on TV on 12 January in spots during shows including Coronation Street.

The campaign also includes digital video and display advertising, as well as PPC, which will be run by Reprise Digital.

Steve Conway, the director of brand marketing at St John Ambulance, said: "This campaign marks a new stage in St John Ambulance’s approach.

"We are deliberately moving away from our harder hitting campaigns, which were useful at getting people to think seriously about first aid. Now we need to educate directly.

"We’ve started with parents because our research showed they are an audience that really wants to know first aid. We hope they share the film and also look at our website for further resources."